Changing device for rotary indexing tables

ABSTRACT

1. Changing device for rotary indexing tables.2. A changing device for rotary indexing tables, having a stand component (12), which is used as a base component and through which a shaft (18) passes, which defines the axis of rotation of tables (2) rotatable by an electric motor and which has an interface (20) for coupling concerned tables (2), which can be fixed in predeterminable rotational positions relative to an respective assigned table unit (8) by means of a clamping device (60), wherein at least two table units (8), differing from each other at least with respect to their clamping devices (60), together with their assigned table (2) as exchange components can be fixed in an interchangeable manner on the base component for their operation.

The invention relates to a changing device for rotary indexing tables,having a stand component, which is used as a base component and throughwhich a shaft passes, which defines the axis of rotation of tablesrotatable by an electric motor and which has an interface for couplingconcerned tables, which can be fixed in predeterminable rotationalpositions relative to a respective assigned table unit by means of aclamping device.

To ensure an exact machining of workpieces, arranged on rotary indexingtables, it is not only required to position the rotary indexing tableprecisely in the concerned rotary positions, but, in order to achieve ahigh machining quality, it is essential to firmly fix the rotaryindexing table in the selected rotary positions. As shown by way ofexample in document DE 103 51 694 C5, it is state of the art in thisrespect to provide a clamping device by means of which, by supplying ahydraulic pressure medium, a clamping force can be generated, whichestablishes a frictional engagement between the table and thestationary, assigned table unit. In the industrial use of rotaryindexing tables, different requirements result for the construction ofthe table unit depending on the various machining tasks, the differenttypes of workpieces to be machined on the rotary indexing table and thetype of tools used for this purpose. This often also applies to theconstructive formation of the clamping device, which, depending on theintended use, for instance has to meet different demands with regard tothe amount of holding torque. To meet changing demands, table units andstand components of various construction are often used alternately fortables of the same size class. Such changing operations, which areadapted to the area of application, represent a considerable cost factorwhile operating of rotary indexing tables.

Based on this problem, the invention addresses the object of providing achanging device permitting an efficient and more cost-effectiveoperation of rotary indexing tables.

According to the invention, this object is achieved by a changing devicehaving the features of claim 1 in its entirety.

Accordingly, the invention provides, as a solution of this problem, achanging device of the genus mentioned above, in which at least twotable units, differing from each other at least with respect to theirclamping devices, together with their assigned table as exchangecomponents can be fixed in an interchangeable manner on the basecomponent for their operation. Because table units of different typesare conceived as exchange components, that can be coupled to the standcomponent via the interface of the shaft of the stand component,required changing operations are limited to the exchange of therespective table unit together with its table. By means of one and thesame stand component as the base component, rotary indexing tables ofdifferent construction, for instance with regard to their clampingdevice, can be operated in this way and, accordingly, a cost-effectiveoperation of rotary indexing tables can be achieved.

In advantageous exemplary embodiments, at one free end of the shaft, andat least partially enclosed by the stand component, an incrementalencoder or an absolute encoder, hereinafter referred to as a rotaryencoder, is arranged and at the other free end the interface for therespective table of a table unit is arranged. The rotary encoder for therotary position of the table can be formed for high-precision rotarypositioning by a rotary encoder as is marketed by the company Dr.Johannes Heidenhaim GmbH, D 83301 Traunreut. Because in the deviceaccording to the invention the same stand component continues to be usedacross changing operations, for high-precision rotary positioning such arelatively expensive component can be used for changing operationswithout any substantial increase in the cost.

Advantageously, the coil winding of an electric motor for driving therespective table is accommodated in the table unit.

In advantageous exemplary embodiments, the cylindrical outercircumference of the stand component forms a guide surface, along whichthe differently formed table units can be placed as exchange units.Changing operations can therefore be performed using little assemblyeffort.

With regard to the different construction of the table units, thearrangement can advantageously be made such that the respective clampingdevice can be at least partially hydraulically operated, wherein the onetype of clamping device between the table and the assigned table unitestablishes the frictional engagement between the rotating table and thetable unit arranged stationarily on the stand component by hydraulicspreading, and wherein the other type of clamping device is providedwith a lamellar frictional engagement device.

In advantageous exemplary embodiments, the stand component is dividedinto two parts, having a rotary guide for the shaft and a foot part,which is flange-like and widens radially outwards in relation to therotary guide, wherein on said foot part the table unit together with therespective type of clamping device is placed in a stationary manner.

Advantageously, a coaxial hollow cylinder can adjoin to the foot part ofthe stand component and encompasses the rotary encoder.

Particularly favorable manufacturing and operating costs can be achievedif the stand component always has the same predeterminable size for allsizes of tables and table units and irrespective of the type of clampingdevice used in the individual case.

The respective rotatable table can be flush with the outer circumferenceof the assigned table unit or, in contrast, be offset radially inwards.

In particularly advantageous exemplary embodiments, on part of the standcomponent at least one rotary seal extends between the rotary guide ofthe stand component and the shaft, wherein said rotary seal isinterrupted by lubrication grooves. With particular advantage, a sealmade of Zurcon (material name by Trelleborg; based on polyurethane) canbe used here, wherein lubricating fluid, supplied from a supply point,is distributed along the axial length of the rotary guide via thelubricating grooves. Furthermore, a variant having gap seals andbearings can be used instead of contact seals to be able to achievehigher rotary speeds.

Below, the invention is explained in detail with reference to exemplaryembodiments shown in the drawing. In the Figures:

FIG. 1 shows a schematically simplified oblique perspective view,cut-away along a central vertical plane, of an exemplary embodiment ofthe changing device according to the invention, and

FIG. 2 shows a correspondingly cut-away, schematically simplifiedoblique perspective view of a second exemplary embodiment of thechanging device according to the invention.

In the figures, a table, which has a circular, planar table surface 4,as is common for rotary indexing tables, is designated by the numeral 2.In the exemplary embodiment of FIG. 1, the table surface 4 is shownwithout any parts, such as workpieces or the like, mounted thereon, butin the exemplary embodiment of FIG. 2, exemplary pieces of equipment 6are shown on the table surface 4. In both exemplary embodiments of FIG.1 and FIG. 2, the table 2 forms a structural unit with an assignedstationary table unit 8, on which the table 2 is rotatably mounted bymeans of a bearing 10 formed by a roller bearing unit of the standardtype. In both exemplary embodiments, the table unit 8 forms a type ofouter housing having mainly circular cylindrical outer wall parts. Thestructural unit, comprising the table 2 and the table unit 8, forms anexchange component which, although it may be of different construction,can be fixed to one and the same base component in the form of a standcomponent 12.

In this respect, FIGS. 1 and 2 show different construction for the table2 together with the table unit 8, which differ mainly in the type ofclamping between the table 2 and the table unit 8. The stand component12 has a circular cylindrical hollow body 14, at the end, at the bottomin the figures, of which there is a foot part 16, which has the form ofa flange that widens radially outwards. The hollow body 14 forms therotary guide for a shaft 18, which defines the axis of rotation for thetable 2 and the upper end of which forms an interface 20, with which theexchange component can be coupled. In this example, as FIG. 1 shows, forthis purpose bolts 20 are provided for a bolted connection to the table2 at the bottom of the table surface 4.

A rotary encoder 24, arranged at the bottom of the foot part 16,interacts with an extension 26 of the shaft 18 to determine itsrotational position and thus the rotational position of the table 2. Inthe rotary guide, formed by the hollow body 14 and in which the shaft 18is guidably supported with and without roller bearings 28, there is arotary distributor for lubricating fluid and other media, which arebeneficial to the seal. The rotary distributor has along the outside ofthe shaft 18 between the rolling bearings 28 a rotary seal 30, in thiscase a Zurcon seal, which is interrupted by supply grooves. Furthermore,a variant having gap seals and bearing instead of contact seals can beused. Starting from a feed point (not shown), to which the lubricant orother medium is routed via a supply line 32, the lubricant or othermedium is distributed along the seal 30 via the lubrication groovesand/or supply grooves. The circular cylindrical outer circumference ofthe hollow body 14 of the stand component 12 forms a guide surface 34,along which the table unit 8 together with the assigned table 2 as anexchange component can be put on the base component formed by the standcomponent 12. As shown in FIG. 1, in the mounted position, an innercollar 38, projecting radially inwards, of an inner housing part 36 ofthe table unit 8 rests against the top surface of the flange-like basepart 16 of the stand component 12. An end sided outer flange 40 of theinner housing part 36 forms the support for a bottom part 42 of theouter housing formed by the table unit 8. An inner circumferentialsurface of the table 2 is guided, sealed by means of a sealing ring 46,at the upper end area of the guide surface 34 of the hollow cylinder 14.

Bolts 48, 50 and 52 are used to connect the table 2 to a shell part 54,which as an outer rotor encompasses a coil winding 56, which is fixed tothe housing bottom part 42 using bolts 58. Also feasible with aninternal rotor. This arrangement forms the electric drive motor of thetable 2. The main difference between the exchange component shown inFIG. 1 and the exchange component shown in FIG. 2 is the construction ofthe clamping device.

In the example of FIG. 1, a plurality of equally formed clamping units60 are arranged at equal distances from each other on a circular lineconcentric to the shaft 18, wherein of said clamping units 60 twoclamping units 60 are visible in FIG. 1. Every clamping unit 60 has astationary device body 62 attached to the inner wall of the housingshell formed by the table unit 8. More specifically, the device body 62is located in an area below the inner bearing part 64 of the bearing 10,which is fixed to the underside of the table surface 4 using bolts 66.In the area between the underside of the inner bearing part 64 and thedevice body 62 there are, from top to bottom, a stationary compressionring 68 connected to the table unit 8, an intermediate ring 70 and alamellar pack 72. The intermediate ring 70, which is connected to thetable 2 by the bolts 48, can be rotated relative to the stationarycompression ring 68.

The lamellar pack 72 is formed by a stacked sequence of disks in themanner of clutch plates, wherein the pack 72 comprises a succession ofstationary lamellas, connected to the stationary compression ring 68 bybolts 74, and movable lamellas, connected to the movable intermediatering 70 by bolts not shown. Every device body 62 has a hydraulicallyactuated piston 76, the end face of which can be used to load and pressthe lamellar pack 72 against the compression ring 78 and theintermediate ring 70, establishing a frictional engagement between thelamellas, by means of which the compression ring 68 and the intermediatering 70 are fixed non-rotatable to each other.

In FIG. 2, components that functionally match those of the example ofFIG. 1 are designated by the same reference numerals as in FIG. 1. Whilein the example of FIG. 1 the circumferential surface 76 of the table 2is set back radially inwards relative to the outer circumference 78 ofthe table unit 8, in the example of FIG. 2 the circumferential l surface76 of the table 2 and the outer circumference 78 of the table unit 8 areflush with each other. Whereas in the example of FIG. 1, a coaxialhollow cylinder 80 is provided at the underside of the foot part 16,wherein said hollow cylinder 80 encompasses the rotary encoder 24 and towhich hollow cylinder 80 the port 82 for the lubricant supply or mediasupply to the conduit 32 is provided, this hollow cylinder 80 is omittedas an optional component in the example of FIG. 2.

In all other respects, however, the stand component 12 fully matchesthat of the example of FIG. 1 as far as its function as a basecomponent, on which exchange components comprising the table 2 togetherwith the table unit 8 of different constructions can be placed, isconcerned. The difference is mainly in the arrangement and constructionof the clamping device, the position of the bearing 10 below theclamping device and the construction of the electric motor, for whichthe shell part 62, connected to the table 2, is not arranged as an outerrotor on the outside of the coil winding 56, but as an inner rotor onthe inside of the coil winding 56.

The clamping units 84, which are hydraulically actuated like theclamping units 60 of FIG. 1, are arranged between a circumferential area86 of the table 2, adjacent to the table surface 4, and a clampingsurface 88, extending in a radial plane and formed by an end surface ina recess in the outer wall of the housing of the table unit 8. Theclamping units 84 comprise a spreader body 90 having an internalpressure chamber 92. By supplying pressure to the pressure chamber 92,the spreader body 90 can be hydraulically spread and generates aclamping force acting between the circumferential area 86 of the table 2and the stationary clamping surface 88 on the table unit 8 to form africtional connection for fixing the relative rotational position. Asshown in FIG. 2, the bearing 10 is arranged below the clamping units 84,wherein, as in FIG. 1, the inner bearing part 64 is fixed to the table 2using bolts 66.

1. A changing device for rotary indexing tables, having a standcomponent (12), which is used as a base component and through which ashaft (18) passes, which defines the axis of rotation of tables (2)rotatable by an electric motor and which has an interface (20) forcoupling concerned tables (2), which can be fixed in predeterminablerotational positions relative to an respective assigned table unit (8)by means of a clamping device (60, 84), wherein at least two table units(8), differing from each other at least with respect to their clampingdevices (60, 84), together with their assigned table (2) as exchangecomponents can be fixed in an interchangeable manner on the basecomponent for their operation.
 2. The changing device according to claim1, characterized in that at one free end of the shaft (18), and at leastpartially enclosed by the stand component (12), a rotary encoder (24) isarranged, and at the other free end the interface (20) for therespective table (2) of a table unit (8) is arranged.
 3. The changingdevice according to claim 1 or 2, characterized in that the coil winding(56) of an electric motor (54) for driving the respective table (2) isaccommodated in the table unit (8), wherein said electric motor (54) isformed as an external or internal rotor.
 4. The changing deviceaccording to claim 1, characterized in that the cylindrical outercircumference of the stand component (12) forms a guide surface (34),along which the differently formed table units (8) can be placed asrespective exchange units.
 5. The changing device according to claim 1,characterized in that the respective clamping device (60, 84) can be atleast partially hydraulically operated, in that the one type (84) ofclamping device (60, 84) between the table (2) and the assigned tableunit (8) establishes the frictional engagement between the rotatingtable (2) and the table unit (8) arranged stationarily on the standcomponent (12) by hydraulic spreading, and in that the other type (60)of clamping device (60, 84) is provided with a lamellar frictionalengagement device (72).
 6. The changing device according to claim 1,characterized in that the stand component (12) is divided into twoparts, having a rotary guide (14) for the shaft (18) and a foot part(16), which is flange-like and widens radially outwards in relation tothe rotary guide (14), wherein on said foot part (16) the table unit (8)together with the respective type of clamping device (60, 84) is placedstationary.
 7. The changing device according to claim 1, characterizedin that a coaxial hollow cylinder (14) adjoins to the food part (16) ofthe stand component (12) and encompasses the rotary encoder (24).
 8. Thechanging device according to claim 1, characterized in that the standcomponent (12) always has the same predeterminable size for all sizes oftables (2) and table units (8) and irrespective of the type of clampingdevice (60, 84) used in the individual case.
 9. The changing deviceaccording to claim 1, characterized in that the respective rotatabletable (2) is flush with the outer circumference (78) of the assignedtable unit (8) or, in contrast, is offset radially inwards.
 10. Thechanging device according to claim 1, characterized in that on part ofthe stand component (12) at least one rotary seal (30) extends betweenthe rotary guide (14) of the stand component (12) and the shaft (18),wherein said rotary seal (30) is interrupted by lubrication grooves ordistribution grooves.